From 1996105e91d8d2022869c4e66c0a0734e363052b Mon Sep 17 00:00:00 2001
From: Mel Zuser <mel.zuser@arista.com>
Date: Fri, 12 Jan 2024 08:57:08 -0800
Subject: [PATCH] added test for empty substring special case

---
 tests/functional/lang/eval-okay-substring-context.exp |  1 +
 tests/functional/lang/eval-okay-substring-context.nix | 11 +++++++++++
 2 files changed, 12 insertions(+)
 create mode 100644 tests/functional/lang/eval-okay-substring-context.exp
 create mode 100644 tests/functional/lang/eval-okay-substring-context.nix

diff --git a/tests/functional/lang/eval-okay-substring-context.exp b/tests/functional/lang/eval-okay-substring-context.exp
new file mode 100644
index 000000000..2fe7f71fa
--- /dev/null
+++ b/tests/functional/lang/eval-okay-substring-context.exp
@@ -0,0 +1 @@
+"okay"
diff --git a/tests/functional/lang/eval-okay-substring-context.nix b/tests/functional/lang/eval-okay-substring-context.nix
new file mode 100644
index 000000000..d0ef70d4e
--- /dev/null
+++ b/tests/functional/lang/eval-okay-substring-context.nix
@@ -0,0 +1,11 @@
+with builtins;
+
+let
+
+  s = "${builtins.derivation { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; }}";
+
+in
+
+if getContext s == getContext "${substring 0 0 s + unsafeDiscardStringContext s}"
+then "okay"
+else throw "empty substring should preserve context"